CD274 and breast carcinoma: Results showed that PD-L1 was lowly expressed in MCF-7 cells and EMT-inactivated breast cancer cells, and abundantly expressed in MDA-MB-231 and BT549 cells, EMT-activated TNBC cells (Figures 6C, D), suggesting that EMT-activated TNBC cells may be associated with increased PD-L1 expression.